Wire bonding is employed to form the electrical interconnections for various different types of microelectronic devices, such as integrated circuits formed on semiconductor die, microelectromechanical systems, passive electronic components, and optical devices. Wire bonding can be utilized to interconnect a microelectronic device to a printed circuit board, a printed wiring board, a leadframe, or the like. Wire bonding can also be utilized to form electrical connections between the device bond pads and electrical conductors included within a two dimensional or three dimensional package containing one or more microelectronic devices. For example, in the case of a Redistributed Chip Package (RCP), wire bonding can be utilized to join the device bond pads to the conductors formed in the RCP layers, which may be, in turn, electrically coupled to a ball grid array formed over the bottom surface of the package.
In one common type of wire bonding, referred to as “ball bonding,” a wire is fed through a specialized tool referred to as a “capillary.” For each wire bond connection, the wire is melted as it emerges through the tip of the capillary and forms a ball-shaped body, which is welded to the bond pad via the application of ultrasonic or thermosonic energy. The capillary then moves away from the ball bond while additional wire is let-out to form the elongated body of the bond wire. To complete the connection, the opposing terminal end of the bond wire is bonded to the contact provided on or included within a leadframe, printed circuit board, microelectronic device package, or the like. Traditionally, gold has been the predominate metal utilized in ball bonding and other types of wire bonding. However, the usage of copper wires in wire bonding has recently become more common in view of the lower electrical resistivity and lower cost of copper as compared to gold and other wire bond materials.
For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction and may omit depiction, descriptions, and details of well-known features and techniques to avoid unnecessarily obscuring the exemplary and non-limiting embodiments of the invention described in the subsequent Detailed Description. It should further be understood that features or elements appearing in the accompanying figures are not necessarily drawn to scale unless otherwise stated. For example, the dimensions of certain elements or regions in the figures may be exaggerated relative to other elements or regions to improve understanding of embodiments of the invention.